The present invention relates to a sealing method and an apparatus therefor, for pneumatically cutting off a vacuum chamber from atmospheric air at the time of execution of vacuum treatment such as glow discharge treatment, etc. and more specifically relates to a sealing method and a sealing apparatus in the case where a support for light-sensitive material is continuously subjected to glow discharge treatment.
Heretofore, various surface treatments, such as vacuum glow discharge treatment, low-temperature plasma treatment such as electrodeless plasma discharge treatment, etc., corona discharge treatment, ultraviolet-ray radiation treatment, and so on, have been carried out onto a plastic film, a metal plate, or the like, for the purpose of improving adhesive force between such a plastic film, a metal plate or the like and a resin or metal layer provided on the surface of the former. It is known that vacuum glow discharge treatment is carried out particularly on a polymer film for the purpose of improvement of the adhesive property, hydrophilic property, dye-affinity, and so on.
The vacuum glow discharge treatment is described, for example, in U.S. Pat. Nos. 3,462,335, 3,761,299, 4,072,769, and so on. Particularly, examples in which glow discharge treatment is preferably used for a support of photographic light-sensitive material without spoiling the flatness and surface characteristic are disclosed in Japanese Patent Unexamined Publication No. Sho-59-56430, Japanese Patent Post-Examination Publication Nos. Sho-60-16614 and Hei-3-39106, etc. and are proposed in Japanese Patent Application Nos. Hei-5-147864, Hei-5-199704, etc. filed by the applicant of the present application.
In the case where a thin-film web is to be subjected to vacuum treatment continuously, the web is led into a vacuum chamber from atmospheric air and back out to atmospheric air after treatment. Accordingly, means for performing leading-in and leading-out of the support while atmospheric air and the vacuum chamber are being sealed from each other are required. As such means, a sealing apparatus in a vacuum vapor depositing apparatus is proposed, for example, in Japanese Patent Unexamined Publication Nos. Hei-1-272767, Hei-1-259169 and Hei-1-287275, PCT-Domestic Publication No. Hei-5-507383, and so on, and an example of a sealing apparatus in a low-temperature plasma treatment apparatus is disclosed in PCT-Domestic Publication No. Hei-5-507383.
FIG. 5 shows a sealing apparatus in a vacuum vapor depositing apparatus described in Japanese Patent Unexamined Publication No. Hei-1-287275. The sealing apparatus described in Japanese Patent Unexamined Publication No. Hei-1-287275 has a structure in which the portion between atmospheric air to a vacuum chamber is partitioned into a plurality of pressure chambers by seal rollers 100 each of which is constituted by a set of three pinch rollers, and a web W is made to move while lapped at a lap angle not lower than 10.degree. around the seal rollers 100. This apparatus is effective for preventing fluttering of the web W having a thickness of about 20 .mu.m, but in the case where the thickness of the web W is not smaller than 80 .mu.m, the moving condition of the web W however varies in accordance with the stiffness of the web W, or the like, so that the quantity of the atmospheric air in a space between the web W and the rollers 100 also varies. For example, in the case of a web W such as a polyester film for a support of photographic light-sensitive material, conveyance performance by the rollers 100 at a lap angle of about 10 degrees is insufficient to solve the problem of fluttering. If fluttering of the web W occurs as described above, slight scratching occurs in a surface portion of the web W contacting the rollers 100 so that the flatness and surface characteristic of the web are spoiled.
On the other hand, a structure in which a web is conveyed while nipped by rollers is disclosed in PCT-Domestic Publication No. Hei-5-507383, but in this structure, sliding contact between the rollers and the web is not avoidable, so that scratching occurs in the web and accordingly the flatness and surface characteristic of the web are spoiled.